KR101536011B1 - Urea line equipped with a coupling having an integrated heating element - Google Patents

Abstract

A urea supply or recovery line (2) comprising a hollow coupling (1) comprising an urea passage and capable of connecting a line to a urea tank, wherein the coupling further comprises a heating filament (9) At least a portion of the filament extends freely within the passageway provided for the urea, and this portion has a spiral or loop shape that can also extend at least partially into the tube attached to the tank and / or tank.

Coupling, line, urea tank, heating filament, electrical terminal, heating element

Description

[0001] UREA LINE EQUIPPED WITH A COUPLING HAVING AN INTEGRATED HEATING ELEMENT [0002]

The present application relates to coupling with integrated heating elements and to the use of said coupling for connecting supply or recovery lines to a urea tank.

The Act on Emissions of Vehicles and Large Freight Vehicles stipulates, among other requirements, the emission of reduced NO _x to the atmosphere. One known method to accomplish this goal is to use a selective catalytic reduction (SCR) process that can reduce nitrogen oxides by injecting a reducing agent, generally ammonia, into the exhaust line. The ammonia can be obtained by pyrolytic decomposition of an ammonia precursor solution, wherein the concentration of the ammonia precursor solution can be eutectic concentration. Such an ammonia precursor is generally a urea solution.

In the SCR process, high levels of NO _x produced in the engine during combustion at optimum efficiency are treated in the catalyst as it is discharged from the engine. This treatment requires accurate concentration and the use of very high quality reductants. Therefore, this solution is precisely metered and injected into the offgas stream, which is hydrolyzed before nitric oxide (NO _x ) is converted to nitrogen (N ₂ ) and water (H ₂ O).

To this end, a tank containing the additive (usually urea) solution and a device for metering the required amount of additive and injecting the additive into the discharge line need to be mounted in the vehicle. To this end, a water soluble urea solution (a eutectic / urea solution with 32.5 wt% urea), which is commonly used, is frozen at -11 캜, so that in order to be injected into the discharge line It is necessary to provide a heating device for liquefying the liquid.

Several systems have been provided in the prior art for this purpose. In general, such systems include relatively expensive heating elements, including one of the specific heating elements or the bypass of the engine cooling tube (see, for example, WO 2006/064001 of the Applicant).

With respect to the use of certain heating elements, it is known to provide heating filaments inside the tank containing the urea solution and, optionally, in the urea (feed and recovery, if necessary) lines. However, according to the present applicant, it has been observed that a problem arises in the connection of the urea lines to the tank. This is because a plug of ice (iced solution) tends to form at and around the connection, and in general, considering that the connection is injection-molded parts made of plastic with a certain thickness Heating through the external heating filament is not efficient.

The present application aims at solving the above problem by providing a coupling for a liquid tank which can quickly remove plugs of frozen liquid which can be formed inside the tank.

To this end, the present invention relates to a hollow coupling, in which a line having a passage for the liquid can be connected to the liquid tank for conveying the liquid according to the hollow coupling, The coupling is additionally provided with a heating filament, and at least a portion of the heating filament extends freely within the passageway provided for the liquid. According to this arrangement, the liquid can be in direct contact with a large heating surface area and the liquid can therefore be heated quickly.

The liquids discussed within the scope of the present invention are those which are liquid under normal use conditions. The liquid is preferably a reducing agent capable of reducing NO _x present in the exhaust gas of the internal combustion engine. Advantageously, the liquid is a solution of a precursor that produces ammonia (an effective reducing agent) in situ in the exhaust gas. The present invention provides excellent results as urea as a precursor, particularly as a water soluble urea solution. Eutectic / urea solutions (containing 32.5 wt% urea and freezing at about -11 캜) are suitable.

The coupling according to the invention is intended for connection to a liquid tank. The tank may be made of any material, preferably a material that is chemically resistant to the liquid. Generally, this material is metal or plastic. In the case of urea, polyolefin resins, particularly polyethylene (and more specifically HDPE or high density polyethylene) constitute the preferred materials.

The coupling according to the invention is therefore intended for coupling a line to the tank which, for example, in the case of a urea, is capable of transferring a liquid, in order to transfer the liquid to the means for injecting said liquid into the exhaust gas of the engine. This variant of the invention (according to the case where the tank is a urea tank) can be applied to any internal combustion engine capable of producing NO _x in the exhaust gas. This may include a fuel return line (i.e., a line that recovers excess fuel not consumed by the engine to the fuel tank) or an engine that does not include the fuel recovery line. This is advantageous for diesel engines, and particularly for diesel engine vehicles.

The outer shape of the coupling according to the invention can be of any shape, and in general the outer shape is a function of the location where the line is to be connected and the respective position of the tank. Preferably, the coupling according to the invention is an elbow coupling, i.e. a coupling which is formed from two sections which are substantially cylindrical, the angle between which forms a substantially right angle. The internal shape of the coupling (i.e., the shape of the passage for the liquid) may be any shape, but is usually substantially cylindrical.

The coupling according to the invention can be coupled to the tank on the one hand and to the line on the other in any known manner. However, the coupling is preferably a rapid connector of the quick connector type well known to those skilled in the art. To this end, the coupling according to the invention is preferably provided with a suitable relief (either internal or external relief) at the two ends of the coupling. Preferably, the relief is arranged inside the side connected to the tank, which may be, for example, one or more grooves carrying protruding seals of the O-ring type, for example . Also, preferably, the relief is arranged on the outside of the side connected to the line, and is composed, for example, of several external projecting grooves.

According to the present invention, the coupling comprises a heating filament, at least a portion of which is free to extend inside the passageway. The term "free" is understood to mean that the filament (optionally provided with a protective coating) is in direct contact with the liquid (urea) present in the passageway but is not embedded in an adiabatic structure such as a flexible tube . Generally, the heated filament is a resistive filament based on a conductive metal provided with a coating (PFA, FEP, PTFE) that is resistant to and / or provides resistance to the urea.

Preferably, said "free part" is in the form of a loop or spiral, and the two ends of this free part are connected to an electrical terminal (for efficient heating of the liquid) . Preferably, the loop or spiral extends from the side of the coupling coupled to the tank, and particularly preferably extends at least partially into the tank and / or into a tube attached to the tank (see below). Preferably, the loop / spiral penetrates into the tank and quickly melts the plug of frozen liquid that can be found in the tank in this manner. Within the scope of the present invention, it is preferred that the loop / spiral "stick out" from the coupling (and consequently from the line) so that it can extend into the tank (or into the tube of the tank) Do. A few centimeters of infiltrated loop / spiral into the tank provide excellent results.

In order to facilitate the insertion of the loops into the coupling (and into the tank if necessary), it is advantageous to support the loops in any form, for example with a finger-shaped guide, At least one fastening relief (clip, notch, etc.) is provided which preferably only allows periodic attachment to the loop so as not to lose too much of the surface area for the loop. The guide is preferably substantially rigid to hold the loop in position in the coupling / tank. Preferably, the at least one fastening relief is for the top of the loop.

According to a particularly advantageous variant of the invention, the electrical terminal is attached to the coupling such that the free ends of the heating filament can be connected to a power supply circuit. In a particularly preferred manner, the heating filaments of the couplings according to the present invention comprise an additional length for not allowing them to freely extend into the coupling but for heating another part of the line, for example.

Also, in a particularly preferred manner, a second heated filament wound in the form of a coil around the outer surface of the line by the electrical terminal can be connected to the power supply circuit irrespective of the filaments of the loop / spiral.

Alternatively, the terminal can be used to connect another heating element in parallel or in series. Preferably, the heating element includes at least one flexible heating portion (i. E. Having a device capable of heating the heating portion, e. G., A resistive element). Preferably, the flexible portion is a flexible heater that is inserted between two flexible films or comprises at least one resistive track attached to the flexible film. Alternatively, the flexible portion can be a simple heating filament or PTC element that can be wound in the form of a coil around the portion to be heated.

Preferably, the electrical terminal is attached to the coupling, wherein the coupling is advantageously provided with an opening through which the filament can be passed and is located within the excrescence provided on the coupling for this purpose. When the coupling is an elbow coupling, the protrusion is generally located at an angle (a vertex of the elbow). Preferably, the terminal is attached to the protrusion by a quick connection, so that the protrusion and / or the terminal are provided with suitable reliefs.

In particular, in order to implement an impermeable attachment, it is advantageous for the terminal to include a protrusion with, for example, at least one seal inserted in the opening provided in the opening of the projection of the coupling, Do.

The present invention also relates to a line for a liquid tank with a coupling as described above, said line being substantially continuous over the entire length of said line, with a heating filament or a couple And an individual heating element connected in series or in parallel with the heating filament of the ring. This filament (element) can be located on the inside of the line or on the outside surface of the line. For reasons of corrosion, the filament is preferably located on the outer surface of the line. In a particularly preferred manner, the element is in the form of a filament wound in the form of a coil around the outer surface of the line.

According to a particularly advantageous variant of the invention, the heating filament is wound in the form of a coil around the outer surface of the line, one end of the heating filament ends being directly connected to a post of the electrical terminal, The other end forms a loop inside the coupling before it is connected to another post of the electrical terminal.

The invention is particularly well suited for couplings made on the basis of plastics, preferably injection-molded plastics. In particular, good results can be obtained with couplings made of polyamide (PA-11, PA-12 or PA-6,6), preferably made of polyamide reinforced with glass fibers in particular. The same material as above is also suitable for the electric terminal when necessary. In this case, it is advantageous to overmould the ends of the heated filament with the plastic forming the terminal.

The present invention also relates to a tank provided with a coupling as described above, and more particularly to a tank for urea solution for exhaust gas of a vehicle. In particular, the tank is provided with a tube formed integrally with an immersed base plate, as described below, and the coupling is attached on the base plate.

The tank can be made with any of the conversion processes known in the case of hollow bodies. Particularly when the tank is made of plastic, specifically HDPE, one preferred process is an extrusion-blow molding process. In this case, a parison is obtained (by one or more parts) by extrusion and then shaped by blow molding in a mold. An integral molding of the tank from a single parison provides excellent results.

To allow the coupling to be connected to the tank, it is advantageous for the tank to be provided with a flange or tube of the type to which the coupling is attached on or in the tank. The tube may be molded integrally with the tank or a portion connected to the tank. According to a preferred variant, the tube is molded integrally with a mounting plate or base plate which is a flat part for sealing the opening in the wall of the tank. The base plate is particularly suitable for the support of accessory through the walls of a hollow body. The base plate has any type of perimeter that is closed up on its own. Usually, this circumference has a circular shape.

In a particularly preferred manner, the base plate is a submerged mounting plate, i.e. a mounting plate that seals the opening in the lower wall of the tank. Within the scope of the present invention, the term "lower wall" is used to designate substantially the same or different shape of the tank, whether the tank is molded integrally or molded from two parison sheets or cut- ), It is understood that it means the lower half portion of the tank. Preferably, the base plate is located at the bottom 1/3 point of the tank, more preferably at the bottom 1/4 point or even at the bottom of the tank. The base plate may be partially located in the lower sidewall and once it is mounted in the vehicle, it is slightly tilted. The position and / or orientation of the base plate depends on the position of the tank in the vehicle and the space occupied around the tank (taking into account the components to be incorporated into the tank).

According to this variant of the invention, the base plate preferably incorporates at least one active storage and / or injection component. It should be understood that the components are manufactured integrally with the base plate or attached to the base plate. This component can be integrated on the inside or outside of the tank with a connection through the plate if necessary. This variant is the subject of the applicant's FR 06/05082, the contents of which are incorporated herein by reference.

Preferably, the base plate in accordance with this variant of the invention incorporates several active storage and / or metering components, and more particularly preferably is a base plate, which is present in the additive tank, Incorporates all active components that come into contact with the liquid additive that reaches the additive tank.

Preferably, the component is selected from the following elements: a pump, a level gauge, a heater, a temperature sensor, a quality sensor, a pressure sensor and a pressure regulator. These factors each have an active role in the additive storage and / or injection system and the fact that the elements are incorporated in a mounting plate that is "immersed" (i.e., where the tank is always empty) They have certain advantages,

- For a level gauge, the lower point is better defined and thus the measurement is less affected by the deformation of the tank,

- For the heater, if frozen, the compartment is developed through the design of the mounting plate combined with the heating system, so that the volume required to operate the pollution control system within the time period required by the vehicle manufacturers (For example, 100 ml in 30 minutes)

- sensors for temperature sensors or other characteristics of the quality sensor or other additives can be easily placed in the critical zone for feeding to the injection system.

The level gauge may be of any type. Preferably, the level gauge is a gauge that does not have, for example, a moving part of a capacitive type.

For a heater, the heater may comprise a heat exchanger of a given capacity or, preferably, a heating element surrounded by a chamber (to create the compartment mentioned above). Preferably, the chamber is integral with the base plate (molded integrally if appropriate).

The base plate immersed in the tank (when the base plate is contained in the tank) can be obtained by any known means, but is preferably obtained by injection molding, and high dimensional accuracy can be obtained by this method.

Preferably, the base plate is based on a fuel-resistant material such as polyacetal, especially POM (polyoxymethylene), or polyamide, and especially reinforced (e.g., reinforced with glass fibers) polyamide grades . Preferably, the base plate is made of polyamide and includes a tube that is molded integrally with the base plate and connected to the coupling as described above.

Figure 1 schematically shows a coupling which is coupled to a line for supplying an urea to an injector or an urea pump.

The present invention is illustrated in a non-limiting manner by the accompanying FIG. According to a particularly preferred variant of the invention, the coupling 1 is connected to a line 2 for supplying the urea to an injector or a urea pump (not shown) ≪ / RTI > This coupling has an elbow coupling 3 with one end 3 snap-fastened to the tube of a urea tank (not shown) and the other end 4 secured to the urea line 2 coupling. To this end, the ends are provided with protruding seals 5 inserted into the outer projecting grooves 7 and the inner grooves 6, respectively. Coupling (1) and line (2) are made of plastic.

An electrical terminal 8, also made of plastic, is snap-fastened to the coupling 1. This coupling forms a heating filament 9 which forms a loop inside the coupling 1 and which is spiral spinally coiled 10 in the shape of a loop around the line 2 (9 ', 9 ").

The heating filament 9 has been inserted into the coupling 1 using a support 11 which for this purpose has a protrusion of the terminal inserted into the provided orifice in the angle / in the form of a finger fastened to an excitation 12, which also includes a projection 13 for this purpose. The finger-shaped support 11 is provided with a locking relief (not shown) which can be fastened to the uppermost part of the loop at the tip of the finger.

Leakage is prevented between the opening in the protrusion 13 of the coupling 1 and the protrusion 12 of the electrical terminal 8 by using the seal 14. [

Generally, the line 2 and the coupling 1 are pre-assembled and the assembly is mounted on a urea tank (or a tube of a urea tank as described above).

Claims (11)

(1) comprising a passage for the urea, the line being connectable to a urea tank, wherein the coupling is further provided with a heating filament (9), at least a portion of the heating filament And this portion has a spiral or loop shape that can also extend at least partially into a tube attached to the tank and / or tank, The line is arranged in series or in parallel with the heating filament (9) of the coupling (1) or the heating filament (9) made integrally with the heating filament of the coupling (1) Comprising an individual heating element connected thereto, The heating filament 9 is wound in the form of a coil around the outer surface of the line, one end 9 ' of the heating filament is directly connected to one post of the electrical terminal and the other end 9 ") Forms a loop inside the coupling before being connected to another post of the electrical terminal. 2. Line (2) according to claim 1, characterized in that the coupling (1) is based on injection-molded plastic. 3. Line (2) according to claim 1 or 2, characterized in that the coupling (1) is formed from two sections which are cylindrical, the angle between the two sections forming a right angle. 3. Coupling device according to claim 1 or 2, characterized in that the coupling (1) is provided with reliefs (6, 7) which enable it to be quickly connected to the tank (2) Line (2). 3. Line (2) according to claim 1 or 2, characterized in that the loop / spiral is supported by a finger-shaped support (11) which facilitates insertion into the coupling (1). Method according to claim 1 or 2, characterized in that an electrical terminal (8) is connected to the loop / spiral and is attached to the projection (13) of the coupling (2) provided with an opening through which the heating filament (9) Characterized in that the protrusion (13) or the electrical terminal (8) is provided with a relief (s) (12) which can be quickly engaged with each other. A urea tank provided with a line (2) according to claim 1 or 2. 8. The urea tank according to claim 7, wherein the coupling (1) is connected to a tube integrally molded with a base plate that seals the opening in the tank wall. Method according to claim 1 or 2, characterized in that an electrical terminal (8) is connected to the loop / spiral and is attached to the projection (13) of the coupling (2) provided with an opening through which the heating filament (9) Characterized in that the protrusion (13) and the electrical terminal (8) are provided with a relief (s) (12) which can be quickly engaged with each other. delete delete

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